Method of error recovery in transmitting and receiving voice service in packet based mobile communication systems

ABSTRACT

Provided is a method of transmitting and receiving data using a persistent allocation scheme in order to effectively support a voice service between a base station and a mobile terminal in a packet based mobile communication system. When an error occurs in transmitting a control information that indicates whether to use a radio resource using the persistent allocation scheme, the base station may retransmit the control information and thereby maintain a communication quality.

TECHNICAL FIELD

The present invention relates to a method of transmitting and receivingdata in a packet based mobile communication system, and moreparticularly, to a method of re-covering from a reception error of acontrol message, which occurs when transmitting and receiving data usinga persistent allocation scheme, in order to effectively support a voiceservice between a base station and a mobile terminal in a nextgeneration packet mobile communication system, which is under discussionfor a standardization.

BACKGROUND ART

3^(rd) Generation Partnership Project (3GPP), one of a number of mobilecommunication standardization organizations, is engaging in a Long TermEvolution (LTE) standardization process and an advanced LTEstandardization process in order to develop a packet based mobilecommunication system standardization. A mobile communication systemgenerally includes a base station constituting a cell, and a mobileterminal used by a user. A plurality of mobile terminals may transmitand receive packet data to and from the base station via a radiochannel.

DISCLOSURE OF INVENTION Technical Problem

An aspect of the present invention provides a method of effectivelycontrolling an activation and a deactivation of a persistent allocationscheme when transmitting and receiving packet data using the persistentallocation scheme, and a method of transmitting and receiving a controlmessage for an error recovery.

Technical Solution

According to an aspect of the present invention, there is provided abase station including: a radio resource allocation unit to allocate aradio resource to a terminal; a control information generation unit togenerate control information based on the allocated radio resource; atransmitter to transmit the control information to the terminal; and areceiver to receive an acknowledgement (ACK) message with respect to thecontrol information.

According to another aspect of the present invention, there is provideda terminal including: a receiver to receive, from a base station,control information associated with data; and a transmitter to transmit,to the base station, an ACK message with respect to the controlinformation. The receiver may receive the data based on the controlinformation.

According to still another aspect of the present invention, there isprovided a base station including: a transmitter to transmit, to aterminal, control information associated with first data, and totransmit the first data to the terminal using the control information;and a receiver to receive an ACK message with respect to the controlinformation. When the ACK message with respect to the controlinformation is not received, the transmitter may retransmit the controlinformation.

Advantageous Effects

According to embodiments of the present invention, when an error occurswherein the error is an activation message not received by a terminaltransmitted from a base station in a persistent allocation scheme, it ispossible to quickly recover from the error.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an example of recovering from atransmission error according to an embodiment of the present invention;

FIG. 2 is a diagram illustrating an operation of a base stationrecovering from a transmission error according to an embodiment of thepresent invention;

FIG. 3 is a diagram illustrating an operation of a terminal recoveringfrom a transmission error according to an embodiment of the presentinvention;

FIG. 4 is a block diagram illustrating a structure of a base stationaccording to an embodiment of the present invention;

FIG. 5 is a block diagram illustrating a structure of a terminalaccording to an embodiment of the present invention; and

FIG. 6 is a block diagram illustrating a structure of a base stationaccording to another embodiment of the present invention.

MODE FOR THE INVENTION

Reference will now be made in detail to exemplary embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. Exemplary embodiments are described below to explain thepresent invention by referring to the figures.

FIG. 1 is a diagram illustrating an example of recovering from atransmission error according to an embodiment of the present invention.Although FIG. 1 shows an embodiment where a base station transmitsdownlink data to a terminal, the present invention may be applicable toan embodiment where the terminal transmits uplink data to the basestation.

Generally, an amount of the downlink data may be too great to betransmitted from the base station to the terminal at once. Therefore,the base station may divide the downlink data into a plurality of datablocks, and sequentially transmit the divided data blocks to theterminal. Hereinafter, the divided data blocks are referred to as firstdata, second data, and the like, respectively.

Referring to FIG. 1, the base station may transmit first data 120 to theterminal. The base station may transmit control information 110associated with the first data 120 prior to transmitting the first data120. According to an embodiment of the present invention, the controlinformation 110 may include information associated with a radio resourceused to transmit the first data 120. The terminal may receiveinformation associated with the radio resource, and receive the firstdata 120 by referring to the received information associated with theradio resource. For example, the terminal may be aware of informationassociated with a time domain or a frequency domain where the first data120 is transmitted, by referring to information associated with theradio resource. The terminal may receive the first data 120 in the timedomain or the frequency domain where the first data 120 is transmitted.

The control information 110 may include modulation and coding schemeinformation associated with the first data 120 or error control schemeinformation associated with the first data 120. The terminal may receivethe modulation and coding scheme information or the error control schemeinformation, and receive the first data 120 using the modulation andcoding scheme information or the error control scheme information.

When the present invention is applied to a 3^(rd) Generation PartnershipProject (3GPP) Long Term Evolution (LTE) system, control information maybe transmitted using a Physical Downlink Control Channel (PDCCH). Also,first data or second data may be transmitted using a Physical DownlinkShared Channel (PDSCH).

Referring again to FIG. 1, the base station may transmit data everypersistent allocation interval 190. After transmitting the first data120, the base station may transmit second data 140 to the terminal. Whencontrol information 130 associated with the second data 140 is differentfrom the control information 110 associated with the first data 120, thebase station may transmit the control information 130 associated withthe second data 140 to the terminal.

The terminal may receive information associated with a radio resource totransmit the second data 140, and modulation and coding schemeinformation or error control scheme information associated with thesecond data 140, which are included in the control information 130. Theterminal may receive the second data 140 using the control information130.

A case where the control information 110 associated with the first data120 is different from the control information 130 associated with thesecond data 140 is referred to as a variable allocation scheme. Thevariable allocation scheme may need to transmit control information withrespect to every piece of data.

In the case of a service with a low data transmission rate such as avoice service, when control information is additionally transmitted withrespect to every piece of data, it may be ineffective. The base stationmay apply the same modulation and coding scheme or the same errorcontrol scheme to every piece of data. In this case, the controlinformation 110 associated with the first data 120 may be the same asthe control information 130 associated with the second data 140.Accordingly, only when initially transmitting data, the base station maytransmit the control information 110. After transmitting the controlinformation 110, the base station may not transmit additional controlinformation. Since a transmission of control information decreases, aradio resource utilization efficiency may be enhanced, which is referredto as a persistent allocation scheme or a semi-persistent schedulingscheme.

In the case of the persistent allocation scheme, an activation messageincluded in the control information 110 may be transmitted prior to datatransmission. The activation message indicates a start of use of theradio resource. Also, a deactivation message included in controlinformation 170 may be transmitted after the data transmission. Thedeactivation message indicates a suspension of use of the radioresource.

Since a status of a radio channel formed between the base station andthe terminal may be unstable, the terminal may not receive controlinformation. When the terminal does not receive the control information,the terminal may not receive first data and second data.

Referring to FIG. 1, in the variable allocation scheme, the controlinformation 110, 130, and 150 may be transmitted with respect the firstdata 120, the second data 140, and third data 160, respectively.Therefore, when the terminal does not receive the control information110 associated with the first data 120, the terminal may abandonreceiving of the first data 120. When the terminal receives the controlinformation 130 associated with the second data 140, the terminal mayreceive the second data 140 using the control information 130.

In the persistent allocation scheme, the control information 110 and 130may be transmitted at particular points in time. When the terminal doesnot receive the control information 110 and 130, the terminal may notreceive the first data 120 and the second data 140.

According to an embodiment of the present invention, when a terminalreceives a control information, the terminal may transmit, to a basestation, an acknowledgement (ACK) message with respect to the controlinformation. When the base station receives, from the terminal, the ACKmessage with respect to the control information, it may be known thatthe base station successfully receives the control information.

Conversely, when the base station does not receive the ACK message withrespect to the control information, whether the terminal successfullyreceives the control information may be uncertain. In preparation for acase where the terminal does not receive the control information, thebase station may retransmit the control information to the terminal.

FIG. 2 is a diagram illustrating an operation of a base stationrecovering from a transmission error according to an embodiment of thepresent invention. The base station may transmit first data 242 and 252,second data 262, and control information 241, 251, and 261using adownlink channel 210.

The control information 241 may include an activation message withrespect to a radio resource. The terminal may receive the first data 242using the radio resource. The transmission error may be defined as thecontrol information 241 or the first data 242 transmitted from the basestation is not received by the terminal.

When the transmission error occurs, the terminal may not recognize thatthe radio resource is activated. Also, since the terminal may be unawareof that the control information 241 or the first data 242 istransmitted, the terminal may not transmit a NACK message 243.

When the base station does not receive an ACK message from the terminal,the base station may retransmit the first data 252. Also, the basestation may retransmit the control information 251 associated with thefirst data 252. The retransmitted control information 251 may include anactivation message with respect to the radio resource, and modulationand coding scheme information or error control scheme informationassociated with the first data 252.

When the terminal receives the retransmitted control information 251 andtransmits an ACK message 253 to the base station using an uplink channel220, the base station may no longer transmit additional controlinformation. The base station may transmit the second data 262 to theterminal but may not transmit control information 261 associated withthe second data 262. The terminal may receive the second data 262 usingthe control information 251 with respect to the second data 262.

When the terminal does not receive, from the base station, adeactivation message with respect to a radio resource, the base stationmay retransmit the deactivation message to the terminal, which issimilar to an embodiment of checking on ACK message and retransmittingan activation message with respect to the radio resource.

FIG. 3 is a diagram illustrating an operation of a terminal recoveringfrom a transmission error according to an embodiment of the presentinvention. A base station may transmit first data 342 and 352, andsecond data 362 using a downlink channel 310. Also, the base station maytransmit control information 341, 351, and 361 using the downlinkchannel 310.

Here, it is assumed that the base station transmits the controlinformation 341 associated with the first data 342 but a transmissionerror occurs.

When the transmission error occurs, the terminal may not receive an ACKmessage and may not transmit a NACK message 343. When the base stationdoes not receive the ACK message from the terminal, the base station mayretransmit the first data 352. The retransmitted control information 351may include modulation and coding scheme information or error controlscheme information associated with the first data 352.

The terminal may receive the first data 352 using the retransmittedcontrol information 351. An activation message with respect to a radioresource may not be received yet at the terminal. The terminal mayretransmit an error recovery request 354 using an uplink channel 320.

The base station may retransmit an activation message 361, in responseto the error recovery request 354.

When the terminal does not receive, from the base station, adeactivation message with respect to a radio message, the base stationmay retransmit the deactivation message to the terminal, which issimilar to an embodiment of retransmitting an activation message withrespect to the radio resource.

FIG. 4 is a block diagram illustrating a structure of a base station 400according to an embodiment of the present invention. The base station400 may include a radio resource allocation unit 410, a controlinformation generation unit 420, a transmitter 430, and a receiver 440.

The radio resource allocation unit 410 may allocate a radio resource toa terminal 450.

The control information generation unit 420 may generate controlinformation by referring to the allocated radio resource. The controlinformation may include information associated with the radio resource.

The transmitter 430 may transmit the control information to the terminal450. According to an embodiment of the present invention, thetransmitter 430 may transmit first data to the terminal 450 using theradio resource. The terminal 450 may receive information associated withthe radio resource, included in the control information, and receive thefirst data using information associated with the radio resource.

According to an embodiment of the present invention, control informationmay include an activation message or a deactivation message with respectto a radio resource. The activation message with respect to the radioresource indicates that a previously unused radio resource is allocatedto a particular terminal and is used to transmit first data. Thedeactivation message with respect to the radio resource indicates that aradio resource used to transmit the first data is released. In a 3GPPLTE system, the activation message and the deactivation message may beindicated as a field of a PDCCH, for example, one bit, or may beindicated as a terminal identifier for a voice service, for example, asemi-persistent scheduling C-RNTI, and the like.

Accordingly, the terminal 450 may receive the activation message withrespect to the radio resource, and transmit the first data using theradio resource associated with the activation message. The terminal 450may receive the deactivation message with respect to the radio resourceand may suspend a transmission of the first data using the radioresource.

When the terminal 450 does not receive the activation message withrespect to the radio resource, the terminal 450 may not receive thefirst data. Also, when the terminal 450 does not receive thedeactivation message with respect to the radio resource, the radioresource may not be retrieved. Accordingly, the base station 400 mayneed to verify whether the terminal 450 receives the activation messageor the deactivation message with respect to the radio resource. Theterminal 450 may receive the control information, and may transmit, tothe base station 400, an ACK message with respect to the receivedcontrol information.

The receiver 440 may receive the ACK message with respect to the controlinformation. When the receiver 440 does not receive the ACK message withrespect to the control information, the base station 400 may not verifywhether the terminal 450 does not receive the control information. Inthis case, the transmitter 430 may retransmit the control information tothe terminal 450.

When the present invention is applied to the 3GPP LTE system, the ACKmessage may be transmitted using a Physical Uplink Control Channel(PUCCH). A content of the ACK message may include a Hybrid ARQ PositiveAcknowledgement (HARQ ACK). A content of a NACK message may include aHARQ NACK.

According to an embodiment of the present invention, the controlinformation may include modulation and coding scheme informationassociated with the first data or error control scheme informationassociated with the first data.

The transmitter 430 may transmit, to the terminal 450, the modulationand coding scheme information or the error control scheme informationassociated with the first terminal. The terminal 450 may receive thefirst data based on the modulation and coding scheme information or theerror control scheme information.

According to an embodiment of the present invention, the transmitter 430may transmit, to the terminal 450, second data using modulation andcoding scheme information associated with the first data or errorcontrol scheme information associated with the first data. Specifically,control information transmitted from the transmitter 430 may beapplicable to a plurality of data as well as particular data.

Also, the transmitter 430 may transmit the first data or the second datausing the radio resource associated with the activation message.

FIG. 5 is a block diagram illustrating a structure of a terminal 500according to an embodiment of the present invention. The terminal 500may include a receiver 510 and a transmitter 520.

The receiver 510 may receive, from a base station 530, controlinformation associated with data.

When the receiver 510 successfully receives the control information, thetransmitter 520 may transmit, to the base station 530, an ACK messagewith respect to the control information. According to an embodiment ofthe present invention, the control information may include informationregarding a radio resource associated with first data. The receiver 510may receive the first data by referring to information associated withthe radio resource.

According to an embodiment of the present invention, the controlinformation may include modulation and coding scheme informationassociated with the first data or error control scheme informationassociated with the first data.

According to an embodiment of the present invention, the controlinformation may include an activation message or a deactivation messagewith respect to the radio resource. The activation message with respectto the radio resource indicates that a previously unused radio resourceis allocated to a particular terminal and is used to transmit the firstdata. The deactivation message with respect to the radio resourceindicates that the radio resource used to transmit the first data isreleased. The receiver 510 may receive the first data using theactivated radio resource.

FIG. 6 is a block diagram illustrating a structure of a base station 600according to another embodiment of the present invention. The terminal600 may include a transmitter 610 and a receiver 620.

The transmitter 610 may transmit, to a terminal 630, control informationassociated with first data. According to an embodiment of the presentinvention, the control information may include information associatedwith a radio resource that is allocated for the first data.Specifically, the control information may include information associatedwith a time domain or a frequency domain where the first data istransmitted.

According to an embodiment of the present invention, the controlinformation may include an activation message with respect to the radioresource. The activation message with respect to the radio resourceindicates that a previously unused radio resource is allocated to aparticular terminal and is used to transmit the first data. The terminal630 may receive the activation message and receive the first data usingthe activated radio resource.

Also, the deactivation message with respect to the radio resourceindicates that the radio resource used to transmit the first data isreleased. The terminal 630 may receive the deactivation message andsuspend the data transmission using the radio resource.

The control information may include at least one of modulation andcoding scheme information associated with the first data and errorcontrol scheme information associated with the first data. The terminal630 may receive the first data using the modulation and coding schemeinformation or the error control scheme information.

The control information is required for the terminal 630 to receive thefirst data. Accordingly, the base station 600 may verify whether theterminal 630 receives the control information. According to anembodiment of the preset invention, when the terminal 630 receives thecontrol information, the terminal 630 may transmit, to the base station600, an ACK message with respect to the control information. Thereceiver 620 may receive the ACK message with respect to the controlinformation.

When the receiver 620 does not receive the ACK message with respect tothe control information, it is uncertain whether the terminal 630receives the control information. Accordingly, the transmitter 610 mayretransmit the control information to the terminal 630.

According to an embodiment of the present invention, the controlinformation may be applicable to second data as well as the first data.In this case, the transmitter 610 may also transmit the second datausing the control information.

Although a few exemplary embodiments of the present invention have beenshown and described, the present invention is not limited to thedescribed exemplary embodiments. Instead, it would be appreciated bythose skilled in the art that changes may be made to these exemplaryembodiments without departing from the principles and spirit of theinvention, the scope of which is defined by the claims and theirequivalents.

1. A base station comprising: a radio resource allocation unit toallocate a radio resource to a terminal; a control informationgeneration unit to generate control information based on the allocatedradio resource; a transmitter to transmit the control information to theterminal; and a receiver to receive an acknowledgement (ACK) messagewith respect to the control information.
 2. The base station of claim 1,wherein, when the ACK message is not received, the transmitterretransmits the control information to the terminal.
 3. The base stationof claim 1, wherein the transmitter transmits first data to the terminalusing the radio resource.
 4. The base station of claim 3, wherein thecontrol information includes modulation and coding scheme informationassociated with the first data or error control scheme informationassociated with the first data.
 5. The base station of claim 4, whereinthe transmitter transmits second data to the terminal using themodulation and coding scheme information or the error control schemeinformation.
 6. The base station of claim 1, wherein the controlinformation includes an activation message or a deactivation messagewith respect to the radio resource.
 7. A terminal comprising: a receiverto receive, from a base station, control information associated withdata; and a transmitter to transmit, to the base station, an ACK messagewith respect to the control information, wherein the receiver receivesthe data based on the control information.
 8. The terminal of claim 7,wherein: the control information includes information associated with aradio resource, and the receiver receives the data using the radioresource.
 9. The terminal of claim 8, wherein the control informationincludes an activation message or a deactivation message with respect tothe radio resource.
 10. The terminal of claim 7, wherein: the controlinformation includes modulation and coding scheme information associatedwith the data or error control scheme information associated with thedata, and the receiver receives the data using the modulation and codingscheme information or the error control scheme information.
 11. A basestation comprising: a transmitter to transmit, to a terminal, controlinformation associated with first data, and to transmit the first datato the terminal using the control information; and a receiver to receivean ACK message with respect to the control information, wherein, whenthe ACK message with respect to the control information is not received,the transmitter retransmits the control information.
 12. The basestation of claim 11, wherein, when the receiver receives the controlinformation, the transmitter transmits second data to the terminal usingthe control information.
 13. The base station of claim 11, wherein thecontrol information includes at least one of information associated witha radio resource allocated with respect to the first data, modulationand coding scheme information associated with the first data, and errorcontrol scheme information associated with the first data.
 14. The basestation of claim 13, wherein the control information includes anactivation message or a deactivation message with respect to the radioresource.